Air return bulkhead with quick release mounting system

ABSTRACT

An air return bulkhead may be removably mounted to the front wall of a cargo container such that the air return bulkhead is releasable and securable without the use of handheld tools. Accordingly, in various embodiments the bulkhead may be quickly and easily uninstalled and reinstalled so as to permit system maintenance, such removal of debris from a filter screen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/013,227 filed Jan. 11, 2008, which is a continuation of U.S.application Ser. No. 10/809,286, filed Mar. 25, 2004, now Pat. No.7,351,136 both of which are herein incorporated by reference in theirentirety.

TECHNICAL FIELD

This relates to temperature control systems, and more particularly tocontrolling airflow in a temperature control system.

BACKGROUND

Temperature-controlled cargo containers, such as refrigerated trailers,are commonly used to transport food products and othertemperature-sensitive products. A refrigerated trailer generallyincludes a refrigeration unit mounted to the front wall of the trailerwith inlet and outlet portions protruding into the interior of thetrailer. The outlet of the refrigeration unit forces cooled air into thetrailer near the ceiling of the trailer, thus causing the cooled air tocycle through the trailer. The inlet of the refrigeration unit ispositioned below the outlet in order to receive air that has cycledthrough the trailer. In some circumstances, the cooled air from theoutlet may “short cycle” and not flow sufficiently to the rear of thetrailer, which can causes a substantial temperature gradient in thetrailer. To prevent the cooled air from leaving the outlet of therefrigeration unit and short cycling immediately to the inlet, a ductsystem may be installed along the ceiling of the trailer and an airreturn bulkhead may be installed on the front wall. The duct systemguides the cooled air from the outlet of the refrigeration unit towardthe rear portion of the trailer. The air return bulkhead effectivelyfunnels the air near the floor of the trailer to the inlet of therefrigeration unit, reducing the likelihood that the cooled air forcedfrom the outlet near the ceiling will short cycle to the inlet.

Typically, air return bulkheads are mounted to the front wall of thetrailer using rivets or screws. Installation or removal of thesebulkheads requires the use of handheld tools such as drills and fastenerdrivers. Conventional bulkheads rely on this method of installationprimarily due to its simplicity and low cost.

However, as the air return bulkhead guides the cycled air from the floorof the trailer to the inlet of the refrigeration unit, debris and otherobjects may become lodged in a filter disposed in the bulkhead plenum orat the inlet of the refrigeration unit. This debris may restrict theairflow path and thereby reduce the efficiency and effectiveness of thetemperature control system. More significantly, however, the presence ofdebris minimizes the heat transfer in the refrigeration unit and thusplaces the unit under considerable strain. The refrigeration unit mayfail if such a condition persists, which in turn may necessitate costlyrepairs.

To remove the debris and clean out the air return path in the bulkhead(or to perform maintenance and repair at the inlet of the refrigerationunit), the bulkhead or a substantial portion thereof is removed fromfront wall of the trailer. The removal or disassembly of the bulkhead isoften time-consuming and inconvenient, as it commonly involves the useof handheld tools and the removal of multiple fasteners.

SUMMARY

An air return bulkhead may be removably mounted to the front wall of acargo container such that the air return bulkhead is releasable andsecurable without the use of handheld tools. Accordingly, in variousembodiments the bulkhead may be quickly and easily uninstalled andreinstalled so as to permit system maintenance, such removal of debrisfrom a filter screen.

In one embodiment, a system may include a cargo container having aninterior at least partially defined by a front wall and sidewalls. Atemperature control unit may be mounted to the front wall and has an airreturn inlet facing the interior of the cargo container. An air returnbulkhead may guide air toward the inlet temperature control unit. Thebulkhead may be mounted so that it can be readily removed andreinstalled without the use of tools.

In another embodiment, an air return bulkhead may include a peripheralportion that is adapted to abut a wall. A face panel may be offset fromthe peripheral portion such that a space is defined between the wall andthe face panel when the peripheral portion abuts the wall. The bulkheadmay further include a toolless mounting means for retaining theperipheral portion in abutment with the wall.

In a further embodiment, a bulkhead includes a peripheral portion thatis adapted to abut a wall and a support portion that is adapted to abutthe wall. A face panel may be offset from the peripheral portion suchthat a space is defined between the wall and the face panel when theperipheral portion abuts the wall. The bulkhead may also include atleast one rib formed in the face panel. The rib may at least partiallydefine a portion of the face panel that is operable to receive a strap.The bulkhead may further include at least one slot formed in thebulkhead. The slot may be operable to receive a flange that extends fromthe wall. In one aspect, the bulkhead may be mountable to the wallwithout the use of handheld tools when the slot receives the flange andthe face panel receives the strap.

The details of various embodiments of the invention are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a cargo container having atemperature control system.

FIG. 2 is a view of the front wall from inside the cargo container ofFIG. 1, with the bulkhead and transition duct removed.

FIG. 3 is a view of the front wall from FIG. 2 with an air returnbulkhead mounted to the front wall in accordance with an embodiment ofthe invention.

FIG. 4 is a perspective view of the air return bulkhead of FIG. 3.

FIG. 5 is a close-up view of a portion of the air return bulkhead ofFIG. 3.

FIG. 6 is a cross-sectional view of the portion of the bulkhead fromFIG. 4.

FIG. 7 is a close-up view of another portion of the air return bulkheadof FIG. 3.

FIG. 8 is a side view of the portion of the bulkhead from FIG. 6.

FIG. 9 is a perspective view of a bracket for mounting an air returnbulkhead to a wall.

FIG. 10 is a side view of the bracket of FIG. 9.

FIG. 11 is a perspective view of connectors for mounting an air returnbulkhead to a wall.

FIG. 12 is a cross-sectional view of one connector from FIG. 11.

FIG. 13 is a perspective view of an air return bulkhead in accordancewith another embodiment.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1, a cargo container includes a temperature controlsystem that is capable of controlling the air temperature within thecontainer. The cargo container is shown as a trailer 100, but any othercargo container, such as a railroad cargo car or a sea vessel transport,may include such a temperature control system in accordance with variousembodiments of the invention. The trailer 100 includes a floor 102, aceiling 104, sidewalls 106, a rear wall 108, and a front wall 110. Therear wall 108 may include an entrance such that cargo 120 may be loadedinto and unloaded from the trailer 100.

The cargo 120 may be temperature-sensitive, or regulations may requirethat the cargo 120 be transported in the trailer 100 at a particulartemperature. For example, fresh produce is usually transported at coolertemperatures in order to maintain freshness or impede degradation. Insuch circumstances, the trailer 100 includes a temperature controlsystem that may have one or more of the following: a temperature controlunit 130, a duct system 140, and an air return bulkhead 150. Thetemperature control system operates to cycle air through the trailer 100such that the air in the trailer is within a predetermined temperatureranged. In one example, temperature control unit 130 may force cool airthroughout the trailer 100 to maintain the air temperature in thetrailer 100 at a desired temperature. Still referring to FIG. 1, thetemperature control unit 130 includes an outlet 134 to force conditionedair into the trailer 100 and an inlet 135 to receive air that isreturning from within the trailer 100. The temperature control unit 130is mounted to the front wall 110 of the trailer 130, and at least aportion 132 of the unit 130 (including the inlet 135 and the outlet 134)faces or protrudes into the trailer. In some embodiments, thetemperature control unit 130 is a refrigeration unit that includes anevaporator to cool the air before it is forced from the outlet 134 intothe trailer.

The duct system 140 includes a transition duct 142 and one or more ductpieces 144. The transition duct 142 is mounted to the ceiling 104 andsurrounds the outlet 134 of the temperature control unit 130. Thetransition duct 142 operates to guide the air forced from the outlet 134to the duct pieces 144 mounted along the ceiling 104. The duct pieces144 may include one or more vents 146 to output the air in various partsof the trailer 100. For example, the temperature control unit 130 mayforce conditioned air from the outlet 134 where the transition duct 142guides the conditioned air to the duct pieces 144 along the ceiling 104of the trailer 100. As the conditioned air passes through the transitionduct 142 and the duct pieces 144, the conditioned air enters into thetrailer 100 through the vents 146 that are incrementally positioned inthe duct pieces 144. The conditioned air is dispersed from the near theceiling 104 of the trailer 100 and may pass all the way to the rearportion of the trailer 100, thus reducing the likelihood of shortcycling.

Still referring to FIG. 1, the air return bulkhead 150 is removablymounted to the front wall 110 of the trailer 100 such that it guides airto the inlet 135 of the temperature control unit 130. The air returnbulkhead 150 includes a face panel 152 that is offset from the frontwall 110 when the bulkhead 150 is properly mounted to the front wall110. As such, air may flow in the space between the face panel 152 andthe front wall 110 toward the inlet 135 of the temperature control unit130. As shown in FIG. 1, the bulkhead 150 may be mounted to the wall 110in an elevated position above the trailer floor 102 so that a gap existsbetween the bulkhead 150 and the trailer floor 102. The bulkhead 150operates to guide air from near the floor 102 of the trailer 100 to theinlet 135 of the temperature control unit 130. Because the air from theoutlet 134 is forced out near the ceiling 104 of the trailer 100, theair return bulkhead 150 reduces the likelihood of short cycling byreturning air that has been cycled to the floor 102 toward the inlet135.

FIG. 2 shows a view of the front wall 110 from inside the trailer 100with the cargo 120, the duct system 140, and the air return bulkhead 150removed. The temperature control unit 130 is mounted to the front wall110 such that an interior portion 132 of the temperature control unit130 faces or protrudes toward the interior of the trailer 100. Theoutlet 134 is positioned near the ceiling 104 of the trailer 100, andthe inlet 135 is positioned closer to the floor 102. In someembodiments, the temperature control unit 130 is mounted to supportposts (not shown in FIG. 2) in the front wall 110, which providestructural support for holding the weight of the temperature controlunit 130. These support posts may be internally embedded in the frontwall 110 such that the posts are not viewable from inside the trailer100.

Still referring to FIG. 2, one or more mounting flanges 310 may besecured to the front wall 110 or to the support posts in the front wall110 of the trailer 100. Similarly, a strap 320 may be secured to thefront wall 110 or to the support posts in the front wall 110. Asexplained below, the flanges 310 and the strap 320 are adapted toreceive an air return bulkhead that is removable without the use ofhandheld tools.

FIG. 3 shows an air return bulkhead 300 removably mounted to the frontwall 110 of the trailer 100 in accordance with an embodiment of theinvention. Although a transition duct (e.g., element 142 in FIG. 1) maypartially or completely surround the outlet 134 of the temperaturecontrol unit 130, the transition duct is not shown in FIG. 3 so as tomore clearly show the interior portion 132 of the temperature controlunit 130. The air return bulkhead 300 may comprise any material that issufficiently durable in the temperature-controlled environment. Forexample, the bulkhead 300 may comprise high-density polyethylene orfiberglass. If the bulkhead 300 comprises a plastic material, thebulkhead 300 may be formed using known vacuum forming methods.

As shown in FIG. 3, the air return bulkhead 300 is mounted to the frontwall 110 such that it abuts at least a portion of the interior portion132 of the temperature control unit 130. When the bulkhead 300 isproperly mounted to the front wall 110 of the trailer, one or moreperipheral portions 304 may be abutted against the front wall 110. Inthe embodiment shown in FIG. 3, the peripheral portions 304 extendsubstantially along the side edges of the bulkhead 300, but a peripheralportion 304 need not extend the full length of an edge. The peripheralportions 304 form a seal with the front wall 110 (and/or the interiorportion 132), thereby preventing a substantial amount of air fromseeping in or out along the peripheral portions 304. A face panel 302 ofthe air return bulkhead 300 is offset from the peripheral portions 304such that a space exists between the front wall 110 and the face panel302. The mounted bulkhead 300 includes at least one air return channelor port 306 near the floor 102 of the trailer. As shown in FIG. 3, thebulkhead 300 may be mounted to the wall 110 in a elevated position abovethe floor 102 so that, in this embodiment, the ports 306 face generallytoward the floor 102. The ports 306 permit air to flow into the spacebetween the face panel 302 and the front wall 110 and to flow toward theinlet 135 of the temperature control unit 130. One or more supportportions 307 are formed in the air return bulkhead 300 such that thesupport portions 307 are offset from the face panel 302 (also shown inFIG. 4) and abut against the front wall 110 of the trailer 100. Thesupport portions 307 provide structural support for the bulkhead 300 andreduce the likelihood of bending or cracking when cargo is pressedagainst the face panel 302.

The air return bulkhead 300 includes a lower end that is wider than theupper end. The upper end spans across the interior portion 132 of thetemperature control unit 130 and surrounds at least a portion of theinlet 135 (FIG. 2). In this embodiment, the face panel 302 at the upperend of the bulkhead 300 extends substantially parallel to and abutsagainst the interior portion 132 of the temperature control unit 130.The lower end of the bulkhead 300 extends substantially from onesidewall 106 of the trailer 100 to the opposing sidewall 106. Thisincreases the amount of return airflow pathways near the floor 102because the air return port 306 may receive air proximal to eachsidewall 106 of the trailer 100 in addition to receiving air fromproximal to the central portion floor 102.

Referring again to FIG. 3, the air return bulkhead 300 also includes afilter element 329. The filter element may be a wire mesh, a plasticscreen, or other filter suitable to prevent debris from entering therefrigeration unit. Multiple discrete filter elements may span the gapsbetween support portions 307 in the plenum area, as shown in FIG. 3.Alternately, a single filter element may be disposed across the entireplenum or opening 306. The filter element may be integrally molded withor affixed to the face panel by adhesives, rivets, fasteners, or othersuitable means.

The air return bulkhead 300 is toollessly mounted to the front wall 110of the trailer 100. In other words, the bulkhead 300 may be mounted to(and removed from) the front wall 110 without the use of handheld tools,such as an air-powered rivet gun or a screwdriver device. In theembodiment shown in FIG. 3, the air return bulkhead 300 is toollesslymounted to the front wall 100 using a strap 320 and mounting flanges310. In other embodiments, however, the bulkhead 300 may be toollesslymounted to the front wall 110 using one or more straps 320, one or moreflanges 310, one or more toolless brackets or connectors, or anycombination thereof Because the air return bulkhead 300 may be quicklymounted to and removed from the front wall 110, a significant amount ofmaintenance/repair time may be saved by using such a bulkhead 300 in atrailer 100 or other cargo container. Moreover, because the air returnbulkhead 300 is toollessly mounted to the front wall 110, the traileroperator does not have to wait until the proper handheld tools areavailable to gain access to the interior side of the bulkhead 300 or theinlet 135 of the temperature control unit 130.

Referring now to FIGS. 3 and 4, each flange 310 is passed through acorresponding slot 312 in an offset portion 308. The tip of each flangemay contact a wall of the corresponding offset portion 308 such that theflanges 310 support the bulkhead 300. For example, as shown in FIG. 3,the flanges 310 may at least partially support the bulkhead 300 in anelevated position above the trailer floor 102. The flanges 310 mayextend from the front wall 110 such that the peripheral portions 304 andthe support portions 307 are abutted against the front wall 110 whilethe face panel 302 and the offset portions 308 are spaced apart from thewall. In some embodiments, the peripheral portions 304 may include agasket that is positioned between the peripheral portions 304 and thefront wall 110 so as to form a sufficient seal.

In addition, the air return bulkhead 300 is retained against the frontwall 110 by the strap 320 that extends across the floating surface 302of the bulkhead 300 and connects to a receptacle 326 using a buckle 325.A loose end 321 of the strap 320 may be pulled to pressure the bulkhead300 against the front wall 110 and the interior portion 132. The strap320 may use any connection means other than a buckle 325 and receptacle326 so as to support the bulkhead 300 against the front wall 110. Aportion of the face panel 302 may be specially adapted to receive thestrap 320. For example, that portion of the face panel 302 may includeribs 309 that slightly protrude from the surface of the face panel 302(as perhaps best shown in FIG. 4) and guide the proper placement of thestrap 320. In another example, that portion of the face panel 302 may betextured or sized appropriately to receive the strap 320. Neither theflanges 310 nor the strap 320 require the use of handheld tools whenmounting or removing the air return bulkhead 300 to the front wall 110,thus permitting the bulkhead 300 to be toollessly mounted to (andremoved from) the front wall 110 of the trailer 100.

FIG. 5 shows a close-up view of the flange 310 and the offset portion308 of the air return bulkhead 300. FIG. 6 shows a cross-section view ofthat flange 310 and that portion 308. The flange 310 is mounted to thefront wall 110 of the trailer 100 using a fastener 314 or otherattachment means so that a gap exists between an angled portion 315 ofthe flange 310 and the front wall 110. In other embodiments, the flange310 may be integral with the front wall 110 with a portion of the flange310 extending outward from the front wall 110. The bulkhead 300 istoollessly mounted to the front wall 110 by maneuvering the tip 316 ofthe flange 310 through the slot 312. The angled portion 315 is thenpassed through the slot 312 such that at least a portion of the bulkhead300 is maintained between the angled portion 315 and the front wall 110.In this embodiment, the angled portion 315 extends from the front wall110 at an upward angle so that the bulkhead 300 is increasinglycompelled toward the front wall 110 as the bulkhead 300 is lowered. Theoffset portion 308 does not necessarily contact the front wall 110because the offset portion 308 is positioned closer to the face panel302 than the support portions 307 and the peripheral portions 304. Thus,the peripheral portions 304 may form a sufficient seal with the frontwall 110 even though the offset portion 308 does not abut the wall 110when mounted on the flanged 310.

Referring to FIGS. 7-8, the strap 320 extends across at least a portionof the face panel 302 and connects to the receptacle 326. The receptacle326 may include any device or mechanism to interlock with the buckle 325or other connection means of the strap 320. In one example, the buckle325 and receptacle 326 may be a track fitting combination provided byKinedyne Corporation of Lawrence, Kans. The receptacle 326 may bemounted to the front wall 110 using any attachment means. The bulkheadis toollessly mounted to the front wall 110 by extending the strap 320along the face panel 302 and connecting the buckle 325 to the receptacle326. This portion of the face panel 302 includes ribs 309 that slightlyprotrude from the face panel 302 and guide the proper placement of thestrap 320. When the buckle 325 is connected to the receptacle 326, theloose end 321 of the strap 320 may be pulled upon to force the facepanel 302 against the interior portion 132 of the temperature controlunit 130. The strap 320 may include a guide piece 328 so as to guide themovement of the strap 320 as the loose end 321 is pulled upon.

In operation, the foregoing structures provide a quick releasefunctionality which permits the bulkhead to be easily removed from andreinstalled on the wall of the trailer without the use of handheldtools. That, in turn, permits an operator to quickly and efficientlyclean or repair the filter element 329. This functionality alsoadvantageously permits the bulkhead to be easily replaced in the eventthat it is damaged by, for instance, a forklift during a loading orunloading operation.

Although the bulkhead 300 depicted in FIGS. 3 and 4 is toollesslymounted to the front wall 110 using mountings flanges 310 and a strap320, other embodiments are not limited to such a combination. Forexample, the air return bulkhead include a set of tongues thatcorrespond to a set of grooves formed the front wall 110 (or viceversa), thus permitting the bulkhead to be toollessly mounted to thefront wall when the tongues are interfaced with the correspondinggrooves.

In other embodiments the bulkhead may be toollessly mounted to the frontwall 110 using toolless connectors or brackets. For example, thebulkhead may include a plurality of spring-loaded reciprocating devicesalong the peripheral portions such that the bulkhead may be snapped intoposition against the front wall 110. In a further example, the bulkheadmay fit onto at least one threaded stud extending from the front wall ofthe trailer. The threaded stud includes a manual-turn knob that screwsonto the threaded portion. A corresponding hole in the bulkhead iscapable of receiving the threaded stud such that the knob may bemanually screwed onto the threaded stud to secure the bulkhead againstthe front wall.

In yet another example, FIGS. 9-10 show a bracket 450 that may befastened to or integrally form with the front wall 110. The bracket 450includes one or more guide portions 452 that define channels 454 betweenthe guide portions 452 and the front wall 110. The guide portions 452are adapted to receive tongue portions 412 that extend from theperipheral portions 404 of the air return bulkhead 400. One bracket 450may be positioned on each of the two sides of the bulkhead 400. As such,the bulkhead 400 may be toollessly mounted to the front wall 110 bymoving each tongue portions 412 into the corresponding channel 454 wherethe tongue portion 412 abuts the guide stop 456, thus causing theperipheral portions 404 to supported against the front wall 110.

In a further example, FIGS. 11-12 show toolless connectors 550 that maybe used to support the air return bulkhead 500 against the front wall110. Similar to the bulkhead described in connection with FIGS. 3 and 4,the bulkhead 500 includes offset portions 508 for receiving flanges thatextend from the front wall 110. In this embodiment, each toollessconnector 550 includes a spring device 554 that presses a plate 552against the bulkhead 500 (either the peripheral portion 504 or the facepanel 502). The spring device 554 is coiled around a shaft 556 that isfastened to the front wall 110 such as by threaded interconnection.

The shaft 556 may be rectangular or include a key so as to prevent theplate 552 from spinning around the shaft 556. Accordingly, the bulkhead500 may be toollessly mounted to the front wall 110 when the flanges areguided through the offset portions 508 (in a manner similar to thatpreviously described in connection with FIG. 3) and the toollessconnectors 550 are adjusted to press against the bulkhead 500.

Referring to FIG. 13, some embodiments of an air return bulkhead 600 mayinclude magnetic elements 650 that permit the bulkhead 600 to betoollessly mounted to the front wall 110. The magnetic elements 650 maybe positioned along the peripheral portions 604 such that the peripheralportions 604 are magnetically attracted to the ferrous or magneticportions of the front wall 110. In addition or in the alternative,magnetic elements 650 may be positioned at the base of the supportportions 607 so that the support portions are compelled toward the frontwall 110. Furthermore, magnetic elements 650 may be positioned in theupper portion of the face panel 602 so that the face panel ismagnetically attracted toward a metallic surface of temperature controlunit 130. The magnetic elements 650 may be embedded in the material ofthe bulkhead 600, embedded into the gasket along the peripheral portions604, or attached to the outer surface of the bulkhead 600. In such anembodiment, the bulkhead 600 may be easily mounted into the properposition on the front wall 110 without the use of handheld tools. Thebulkhead 600 may be removed from the front wall by manually pulling thebulkhead 600 away from the wall 110 to separate the magnetic elements650 from the front wall 110.

Other embodiments of the bulkhead are secured to the front wall of thetrailer with a hook-and-loop fastener system such as that sold under thetradename Velcro™. For instance, adhesive strips having hooks disposedthereon may be adhered to wall-facing side of the peripheral flange andadhesive strips having loops disposed thereto may be affixed tocorresponding surfaces on the front wall of the trailer. As such, thebulkhead may be manually secured and removed from the wall without theuse of handheld tools.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. A method of using an air return bulkhead in a refrigerated trailer,comprising: releasably engaging the air return bulkhead with a pluralityof mounting brackets coupled to a trailer wall by extending each of themounting brackets through a corresponding slot in an offset portion ofthe bulkhead positioned in an internal portion of the bulkhead, theinternal portion of the bulkhead completely surrounding the offsetportion, so that a peripheral portion of the bulkhead is urged againstthe trailer wall; releasably engaging a face panel of the bulkhead witha strap that extends from the trailer wall, the face panel being coupledto the peripheral portion to define a plenum between the face panel andthe trailer wall, and the strap being adjustable to urge the peripheralportion of the bulkhead toward the trailer wall, wherein the bulkhead istoollessly mounted to the trailer wall using the strap and the mountingbrackets; and manually removing the bulkhead from the trailer wallwithout the use of handheld tools.